1. Field of the Invention
The present invention relates to, for example, a media communication apparatus and a media communication program product, which, by automatically selecting a telecommunications carrier offering the lowest communication charge on the basis of communication charges set for each of IP (Internet Protocol) telephony telecommunications carriers and automatically identifying the communication protocol of the telecommunications carrier (server for session management), can receive a communication connection service provided by the telecommunications carrier through a communication path to which the lowest communication charge applies.
2. Description of the Prior Art
In recent years, the Internet has become widespread as a giant network formed by connecting, through leased lines, computer networks (e.g., a LAN (Local Area Network) and WAN (Wide Area Network)) scattered across various locations, thereby making many services available.
For example, there is provided an IP telephony communication connection service as shown in National Publication of International Patent Application No. 2003-506929, as one of services utilizing the Internet. There is also provided an IP telephony communication connection service which utilizes an IP telephony-specific network having the same mechanism as the Internet. The Internet itself and an IP telephony-specific network which is not directly connected to the Internet are generically called IP networks, and voice communication is performed through such an IP network in an IP telephony communication connection service. In this case, in an IP network, voice data is divided into small units (packets) and delivered to the other end, where the packets are reconstructed into the original voice. There is available VoIP (Voice over IP) as a technique for implementing such voice communication.
IP telephony generally adopts a set of communication conventions (communication protocol) called H.323 standardized by the Telecommunication Standardization Sector (ITU-T) of the International Telecommunication Union (ITU). However, since H.323 has, e.g., the disadvantage that it is hard to work in cooperation with other Internet applications, SIP (Session Initiation Protocol) is attracting attention as a communication protocol for eliminating the disadvantage.
SIP is a set of communication conventions (communication protocol such as VoIP used in conversion of voice communication to IP) which are established by the IETF (Internet Engineering Task Force) and documented in an RFC (Request for Comment) SIP has, e.g., the advantages that it is text-based and can be decoded, and thus facilitates development, that it has an openness which allows not only specialists but also clients (terminals) to deal with it, and that services between clients (terminals) can be enriched because it is a protocol which establishes a session.
Now, various telecommunications carriers provide IP telephony communication connection services utilizing the advantages of SIP. In this case, the communication protocol, SIP, is used to establish, change, and end a session (manage a session) and has no concern with the contents of the session. Each telecommunications carrier sets up a SIP server for performing such session management. For example, when a client (terminal) is to communicate voice data in packets, session management on the basis of SIP messages of a predetermined type is performed between the client (terminal) and the SIP server. When a session is established, voice data is delivered to a desired party and is reconstructed. Note that the format of a SIP message is similar to, e.g., a standard message format utilized in the Internet (such as SMTP (Simple Mail Transfer Protocol) or HTTP (HyperText Transfer Protocol)), and the procedures for SIP messages are defined by, e.g., a request method (request message) such as an INVITE (invitation) or ACK (acknowledgment) and a response (status) code (response message) such as a 100Trying (provisional response) or 200ok (successful response).
A media communication apparatus (IP telephone adaptor) provided by a specific telecommunications carrier when the client (terminal) makes a connectivity contract with the telecommunications carrier can establish a session only with the telecommunications carrier through SIP messages and cannot establish a session with any other telecommunications carrier through SIP messages. This is because a session is performed through SIP messages of a type unique to each telecommunications carrier in accordance with the specifications and settings of a SIP server of the telecommunications carrier. For this reason, a media communication apparatus specific to another telecommunications carrier needs to be separately prepared to establish a session with the other telecommunications carrier through SIP messages. In this case, a client (terminal) needs to prepare a plurality of media communication apparatuses specific to telecommunications carriers, respectively, in order for the client (terminal) to receive the IP telephony communication connection services provided by the plurality of telecommunications carriers. As a result, the construction of a system for performing voice communication through an IP network becomes complicated, and at the same time, the cost of equipment to that purpose increases.
This problem can be solved with a media communication apparatus and media communication program which can establish a session through SIP messages for each of the plurality of telecommunications carriers to communicate media. However, such a media communication apparatus and media communication program are not known at present.
Also, there is already known an IP telephone system with an LCR (Least Cost Routing) function or ACR (Automatic Carrier Routing) function as a telephone communication connection technique (see, e.g., Japanese Patent Laid-Open No. 2004-129134 and Japanese Patent Laid-Open No. 2004-134825). In such a service, it is possible to automatically select a communication path to which the lowest communication charge applies on the basis of the address (e.g., an IP telephone number, general subscriber telephone number, cellular telephone number, IP address, or the like) of a party to be called input at the time of call origination.
In this case, when a call is originated by inputting the address of the party to be called, the IP telephone system selects a telecommunications carrier which offers the lowest communication charge from a selection table (table in which communication charges for each of telecommunications carriers are registered in advance) on the basis of the address and establishes a connection for speech through the communication path of the telecommunications carrier. This allows mutual speech.
However, the above-described IP telephone system is one which is compatible with a communication protocol compliant with H.323 and is not compatible with a communication protocol compliant with SIP in the spotlight now. Accordingly, the system cannot be directly applied to a media communication apparatus and media communication program which establish a session through SIP messages of a type different for each of telecommunications carriers and communicate media.